Communication device

ABSTRACT

A communication device which efficiently dissipates locally generated heat, and at the same time is small in size and light in weight, is provided. A high-efficiency heat-dissipating fin section having fins disposed on an heat pipe which is bent into an S shape is mounted on a high-temperature heat-generating section that generates high-temperature heat. A heat-dissipating fin section having fins disposed on a heat-receiving plate thereof is mounted on a low-temperature heat-generating section that generates heat having a lower temperature than that of the high-temperature heat generated by the high-temperature heat-generating section. This makes it possible to efficiently dissipate heat and reduce the size and weight of the communication device.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to a communication device provided in a basestation for cellular phones, and more particularly to a communicationdevice which generates heat.

(2) Description of the Related Art

The usage rate of cellular phones has been becoming so high thatcommunication devices used in base stations are demanded to be higher inoutput. Communication devices higher in output generate larger amountsof heat, which affect reliability of operations thereof. Therefore, howto attain efficient heat dissipation is a key problem of recentcommunication devices. Provision of heat-dissipating fins is amongconventional solutions thereto.

In conventional communication devices, a single heat-dissipating finsection, for example, is provided for each heat-generating electronicmodule (see e.g. page 3 and FIGS. 1 and 2 of Japanese Unexamined PatentPublication No. 6-310883). Further, on electronic modules different inthe amount of heat generation, there are mounted respective singleheat-dissipating fin sections which are different in the height of fins(see e.g. page 6 and FIG. 10 of Japanese Unexamined Patent PublicationNo. 11-298180).

FIG. 17 is a perspective view showing an example of a conventionalcommunication device having a heat-dissipating fin section attachedthereto. FIG. 18 is an exploded perspective view of the conventionalcommunication device shown in FIG. 17 with a digitaldistortion-compensating unit and a converter unit removed therefrom.FIG. 19 is an exploded perspective view of the conventionalcommunication device with a power supply unit further removed from theapparatus in the state shown in FIG. 18.

As shown in FIGS. 17 to 19, the communication device 100 is comprised ofa heat-dissipating fin section 101, a digital distortion-compensatingunit 102, a converter unit 103, power supply units 104, 105, a poweramplifier unit 106, and a front panel 107.

The heat-dissipating fin section 101 is comprised of an aluminumheat-receiving plate and a plurality of aluminum fins protrudingtherefrom. The power supply unit 105 and the power amplifier unit 106are mounted on the heat-receiving plate. The heat-dissipating finsection 101 dissipates heat generated by the power supply unit 105 andthe power amplifier unit 106. The heat-dissipating fin section 101 has agenerally rectangular parallelepiped shape, and extends over the entiresurface of one side of the communication device 100.

The digital distortion-compensating unit 102 is a printed board on whichis mounted a circuit for compensating for distortions of a digitalsignal. The digital distortion-compensating unit 102 is mounted on theheat-dissipating fin section 101 in a manner covering the power supplyunit 104 mounted on the heat-dissipating fin section 101.

The converter unit 103 is a printed board on which is mounted a circuitfor frequency conversion of a signal.

The power supply unit 104 is a printed board on which is mounted acircuit for supplying power to circuits. The power supply unit 105 is apackaged power supply module which supplies power to circuits. The powersupply unit 104 is mounted on the heat-dissipating fin section 101 in amanner covering the power supply unit 105 and the power amplifier unit106 mounted on the heat-dissipating fin section 101.

The power amplifier unit 106 is an L-shaped printed board on which ismounted a circuit for amplifying a high-frequency signal. This printedboard has power transistors mounted thereon for amplifying thehigh-frequency signal.

The front panel 107 is a panel attached to a front side of thecommunication device 100 when it is received in the rack.

Heat generated by the power supply unit 105 and the power amplifier unit106 is dissipated by the heat-dissipating fin section 101, whereby thetemperature of the communication device 100 is prevented from risingbeyond a predetermined temperature. In the communication device 100constructed as above, when the amount of heat generated by the powersupply unit 105 and the power amplifier unit 106 is increased, it isnecessary to increase the area of the heat-receiving plate of theheat-dissipating fin section 101, and the height and length of the finsto enhance the heat dissipation efficiency.

Now, heat emitted from power transistors is very large, and by farlarger than heat emitted from power supply circuits or the like.Therefore, heat emitted from the power amplifier unit 106 having thepower transistors mounted thereon is larger than heat emitted from thepower supply unit 105, which prevents heat from being uniformlydistributed in the heat-receiving plate of the heat-dissipating finsection 101. Further, non-uniform heat distribution is also causeddepending on the mounting locations of the power transistors. Therefore,to simply increase the size of the heat-dissipating fin section 101 isnot enough, for example, to realize uniform heat distribution all overthe heat-dissipating fin section 101 and conduction of heat to thedistal ends of fins.

As described above, although the size of the heat-dissipating finsection is increased for coping with an increase in the amount of heatgeneration caused by the increased output, heat locally emitted from theheat-generating portions of the apparatus is not uniformly conducted tothe entire heat-dissipating fin section, so that some fins do not servethe function of dissipating heat, which degrades the heat dissipationefficiency. Further, there is a demand for a communication device smallin size and weight so as to facilitate maintenance and mounting of theapparatus in a rack.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstances,and an object thereof is to provide a communication device whichefficiently dissipates heat locally emitted from heat-generatingportions, and at the same time is small in size and weight.

To attain the above object, the present invention provides acommunication device that generates heat. The communication deviceaccording the present invention is characterized by comprising ahigh-temperature heat-generating section that generates high-temperatureheat, a first heat-dissipating fin section mounted on saidhigh-temperature heat-generating section, said first heat-dissipatingfin section having a heat pipe and fins provided on said heat pipe, alow-temperature heat-generating section that generates low-temperatureheat having a lower temperature than that of the high-temperature heatgenerated by said high-temperature heat-generating section, and a secondheat-dissipating fin section mounted on said low-temperatureheat-generating section, said second heat-dissipating fin section havinga heat-receiving plate, and fins provided on said heat-receiving plate.

The above and other objects, features and advantages of the presentinvention will become apparent from the following description when takenin conjunction with the accompanying drawings which illustrate preferredembodiments of the present invention by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a communication device according to thepresent invention as viewed from the right side of the front thereof;

FIG. 2 is a front view of a rack containing the communication deviceshown in FIG. 1;

FIG. 3 is a perspective view of the communication device according tothe present invention as viewed from the left side of the front thereof;

FIG. 4 is a perspective view of the communication device with aconverter unit and a digital distortion-compensating unit appearing inFIG. 3 being removed therefrom;

FIG. 5 is an exploded perspective view of the communication device shownin FIG. 4;

FIG. 6 is an exploded perspective view of the communication device in astate in which the power supply unit appearing in FIG. 5 is removedtherefrom;

FIG. 7 is an exploded perspective view of the communication device in astate in which the cover appearing in FIG. 6 is removed therefrom;

FIG. 8 is an exploded perspective view of the communication device in astate in which a high-frequency board and a high-efficiencyheat-dissipating fin section appearing in FIG. 7 are removed therefrom;

FIG. 9 is a side view of the communication device, which is useful inexplaining the layout of power transistors;

FIG. 10 is a diagram which is useful in explaining the high-efficiencyheat-dissipating fin section, in which (A) of FIG. 10 is a top view ofthe high-efficiency heat-dissipating fin section, (B) of FIG. 10 is afront view of the same, and (C) of FIG. 10 is a side view of the same;

FIG. 11 is a diagram which is useful in explaining a protection covercovering the high-efficiency heat-dissipating fin section, in which (A)of FIG. 11 is a top view of the protection cover on the section, (B) ofFIG. 11 is a front view of the same, and (C) of FIG. 11 is a side viewof the same;

FIG. 12 is a cross-sectional view of part of the high-efficiencyheat-dissipating fin section taken on line A—A of FIG. 9;

FIG. 13 is a diagram showing a variation of the high-efficiencyheat-dissipating fin section shown in FIG. 12;

FIG. 14 is a perspective view of the communication device having a coverattached thereto;

FIG. 15 is a view showing a cross-section of the communication deviceshown in FIG. 14 and a flow of air;

FIG. 16 is a cross-sectional view of the communication device, on whichanother cover is attached thereto, for comparison of flows of coolingair passing between fins;

FIG. 17 is a perspective view showing an example of a conventionalcommunication device having a heat-dissipating fin section mountedthereon;

FIG. 18 is an exploded perspective view of the conventionalcommunication device in a state in which a digitaldistortion-compensating unit and a converter unit are removed from theapparatus in the state shown in FIG. 17; and

FIG. 19 is an exploded perspective view of the conventionalcommunication device in a state in which a power supply is furtherremoved from the apparatus in the state shown in FIG. 18.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described in detail with reference to thedrawings showing a preferred embodiment thereof. FIG. 1 is a perspectiveview of a communication device according to the present invention asviewed from the right side of the front thereof. FIG. 2 is a front viewof a rack containing the communication device shown in FIG. 1.

The communication device 10 shown in FIG. 1 is comprised of ahigh-efficiency heat-dissipating fin section 20, a protection cover 30,a heat-dissipating fin section 40, a guide rail 50, and a front panel60.

The high-efficiency heat-dissipating fin section 20 is mounted on orprovided for a high-temperature heat-generating section including acircuit module or a printed board on which are mounted parts thatgenerate high-temperature heat. The high-efficiency heat-dissipating finsection 20 includes a heat-receiving plate 21 in contact with thehigh-temperature heat-generating section, for receiving heat therefrom,a heat pipe 22 brazed to the heat-receiving plate 21 for heat transport,and fins 23 brazed to the heat pipe 22, for dissipating the heattransported thereby. The high-efficiency heat-dissipating fin section 20transports the heat from the heat-receiving plate 21 to all the fins 23via the heat pipe 22 to thereby efficiently dissipate the heat.

The protection cover 30 covers the fins 23 of the high-efficiencyheat-dissipating fin section 20 and is rigidly fixed to theheat-receiving plate 21. The protection cover 30 is provided forpreventing damages to the high-efficiency heat-dissipating fin section20 e.g. due to contact of the fin section 20 with an external object.

The heat-dissipating fin section 40 is mounted on a low-temperatureheat-generating section including circuit modules and/or printed boardson which are mounted parts that generate low-temperature heat lower intemperature than that of the high-temperature heat generated by thehigh-temperature heat-generating section. The heat-dissipating finsection 40 includes a heat-receiving plate 41 in contact with thelow-temperature heat-generating section, for receiving the heattherefrom, and fins 42 crimped to part of the heat-receiving plate 41.It should be noted that the heat-dissipating fin section 40 is analuminum heat-dissipating fin section (crimped fins) in general use. Theheat-dissipating fin section 40 has a guide rail 50 attached thereto forpositioning the communication device 10 when the communication device 10is received in the rack 70 shown in FIG. 2.

The heat-receiving plate 41 of the heat-dissipating fin section 40 formsa body of the communication device 10. The circuit modules and/orprinted boards which generate high-temperature heat or low-temperatureheat are secured to a surface of the heat-receiving plate 41 opposite toa surface thereof from which the fins 42 protrude. Further, theheat-receiving plate 41 extends toward the high-efficiencyheat-dissipating fin section 20 and has the heat-receiving plate 21 ofthe fin section 20 secured thereto.

The front panel 60 is fixed to the heat-receiving plate 41 of theheat-dissipating fin section 40. The front panel 60 has a grip 61attached thereto, for enabling the communication device 10 to be easilypushed in and drawn out from the rack 70 shown in FIG. 2.

As described above, on the high-temperature heat-generating section thatgenerates high-temperature heat, there is mounted the high-efficiencyheat-dissipating fin section 20 having the fins 23 brazed to the heatpipe 22 thereof, for efficient heat dissipation, while on thelow-temperature heat-generating section that generates thelow-temperature heat lower in temperature than that of thehigh-temperature heat generated by the high-temperature heat-generatingsection, there is mounted the heat-dissipating fin section 40 having thefins 42 crimped to the heat-receiving plate 41 thereof, for heatdissipation. This makes it possible to efficiently dissipate locallygenerated heat, without producing portions to which the locallygenerated heat is not properly transported, which can be caused by anincrease in the size of the heat heat-dissipating fin section.

Further, since the high-temperature heat generated on thehigh-temperature heat-generating section is dissipated by thehigh-efficiency heat-dissipating fin section 20, the heat-dissipatingfin section 40 is only required to have a shape suitable for dissipatingthe heat generated by the low-temperature heat-generating section. Thismakes it possible to decrease the size of the communication device.

The rack 70 shown in FIG. 2 is installed on a base station for cellularphones. The rack 70 accommodates a plurality of the above describedcommunication devices 10, which amplify radio signals for transmission.The rack 70 is provided with cooling fans 71 for blowing wind (coolingair) from below for air-cooling the communication devices 10. Further,the rack 70 has received signal-amplifying sections 72 for amplifyingreceived radio signals, and a control section 73 for controlling thecommunication devices 10 and the received signal-amplifying sections 72.

FIG. 3 is a perspective view of the communication device according tothe present invention as viewed from the left side of the front thereof.As shown in FIG. 3, in the communication device 10, the heat-receivingplate 41 of the heat-dissipating fin section 40 has bosses arranged onthe surface opposite to the surface from which the fins 42 protrude, anda converter unit 80, and a digital distortion-compensating unit 81 aresecured to the opposite surface with screws. The converter unit 80 is aprinted board on which is mounted a circuit for frequency conversion ofa signal. The digital distortion-compensating unit 81 is a printed boardon which is mounted a circuit for compensating for distortions of adigital signal.

It should be noted that although the position of the guide rail shown inFIG. 3, and FIG. 4 to FIG. 8, referred to hereinafter, is different fromthat of the guide rail appearing in FIG. 1, the guide rail may bedisposed as shown in FIG. 3 and FIG. 4.

FIG. 4 is a perspective view of the communication device with theconverter unit and digital distortion-compensating unit removed from thedevice in the state shown in FIG. 3. FIG. 5 is an exploded perspectiveview of the communication device shown in FIG. 4. When the converterunit 80, digital distortion-compensating unit 81, and front panel 60appearing in FIG. 3 are removed, the communication device appears asshown in FIG. 4.

As shown in FIGS. 4 and 5, the heat-receiving plate 41 of theheat-dissipating fin section 40 has the bosses formed on the surfaceopposite to the surface from which the fins 42 protrude, and a powersupply unit 82 is secured to the opposite surface with screws. The powersupply unit 82 is a printed board on which is mounted a circuit forsupplying power to circuits.

Further, a power supply unit 83 having a generally rectangularparallelepiped shape and an L-shaped cover 84 are secured to the surfaceof the heat-receiving plate 41 opposite to the surface from which thefins 42 protrude, with screws.

FIG. 6 is an exploded perspective view of the communication device withthe power supply unit being removed from the state shown in FIG. 5. Asshown in the figure, on the surface of the heat-receiving plate 41 ofthe heat-dissipating fin section 40 opposite to the surface from whichthe fins 42 protrude, there is formed a rectangular frame 43 forreceiving the power supply unit 83 therein. The frame 43 is formed incontraposition with the fins 42.

The power supply unit 83 is a packaged power supply module for supplyingpower to circuits. The power supply unit 83 is in direct contact withthe heat-receiving plate 41, and secured to the same with screws.

The fins 42 protrude from a location of the heat-receiving plate 41opposite to a location to which the power supply unit 83 is secured. Dueto this construction, heat generated by the power supply unit 83 isconducted to the heat-receiving plate 41, and dissipated through thefins 42.

FIG. 7 is an exploded perspective view of the communication device withthe cover appearing in FIG. 6 being removed therefrom. As shown in FIG.7, the heat-receiving plate 41 of the heat-dissipating fin section 40has an L-shaped frame 44 formed on the surface thereof opposite to thesurface from which the fins 42 protrude. The frame 44 is configured tobe covered by the cover 84, and has a high-frequency board 85 fixed tothe inside thereof.

FIG. 8 is an exploded perspective view of the communication device withthe high-frequency board and high-efficiency heat-dissipating finsection appearing in FIG. 7 being removed therefrom. As shown in FIG. 8,when the high-frequency board 85 is removed, there appears a poweramplifier unit 86 secured to the inside of the frame 44.

The power amplifier unit 86 is an L-shaped printed board on which ismounted a circuit for amplifying a high-frequency signal. The poweramplifier unit 86 has power transistors mounted thereon for amplifyingthe high-frequency signal. Some of the power transistors which are highin output generate heat having a temperature by far higher than heatgenerated by the power supply unit 83.

The power amplifier unit 86 and the high-efficiency heat-dissipating finsection 20 are rigidly fixed to the heat-receiving plate 41 of theheat-dissipating fin section 40 in a manner opposed to each other withthe heat-receiving plate 41 interposed therebetween. Due to thisconstruction, heat generated by the power amplifier unit 86 isdissipated by the high-efficiency heat-dissipating fin section 20.

FIG. 9 is a side view of the communication device, which shows thelayout of the power transistors mounted therein. As shown in FIG. 9, theL-shaped power amplifier unit 86 is rigidly fixed to the inside of theframe 44 of the heat-receiving plate 41. The power amplifier unit 86 hasthe transistors 86 a to 86 h mounted thereon. The power amplifier unit86 generates heat as a sum of respective portions of heat generated bythe transistors 86 a to 86 h which locally generate heat having veryhigh temperatures. The heat locally generated by the transistors 86 a to86 f is dissipated by the high-efficiency heat-dissipating fin section20.

FIG. 10 is a diagram which is useful in explaining the high-efficiencyheat-dissipating fin section, in which (A) of FIG. 10 is a top view ofthe high-efficiency heat-dissipating fin section, (B) of FIG. 10 is afront view of the same, and (C) of FIG. 10 is a side view of the same.

As shown in FIG. 10, the high-efficiency heat-dissipating fin section 20has the fins 23 rigidly fixed to the heat pipe 22 by brazing such thatthe fins 23 are disposed perpendicularly to the plane of the heat pipe22. It is preferred from a space-saving point of view that the heat pipe22 is bent such that e.g. two or more layers (three layers, four layers,. . . ) of fins can be arranged on the heat pipe. In this case, inaddition to a configuration of no fins being arranged at a bent portion(portion bent for connecting the above layers to each other, as shown in(B) of FIG. 10) of the heat pipe, it is possible to contemplate aconfiguration in which fins are also arranged at the bent portion. Itshould be noted that in the illustrated example, the length (representedby L in (C) of FIG. 10) of the bent portion is set to be slightly largerthan the length of the fins 23 provided on a first layer (layer disposedtoward the heat-receiving plate 21) so as to keep the fins on the firstlayer from contact with a portion of the heat pipe 22 to which a secondlayer of the fins is fixed.

The heat pipe 22 has a bottom surface thereof fixed to theheat-receiving plate 21 by brazing. The heat pipe 22 is a plate-shapedpipe which is filled with liquid, such as fluorocarbon or the like, as aworking fluid, for enhancing heat transfer efficiency.

As described above with reference to FIGS. 8 and 9, the heat-receivingplate 21 of the high-efficiency heat-dissipating fin section 20 issecured to a location opposed to the power amplifier unit 86 generatinghigh-temperature heat with the heat-receiving plate 41 of theheat-dissipating fin section 40 disposed therebetween. Due to thisconstruction, the high-temperature heat generated by the power amplifierunit 86 is transferred to the heat-receiving plate 21 of thehigh-efficiency heat-dissipating fin section 20.

The heat transferred to the heat-receiving plate 21 is transferred tothe heat pipe 22. The heat transferred to the heat pipe 22 istransported in directions indicated by arrows in FIG. 10(B) due totemperature differences between the ends of the heat pipe 22.Accordingly, the heat generated by the power amplifier unit 86 isdissipated by the first and second layers of fins 23 rigidly fixed tothe lower and upper portions of the heat pipe 22, respectively.

FIG. 11 is a diagram which is useful in explaining the protection covercovering the high-efficiency heat-dissipating fin section 20 in which(A) of FIG. 11 is a top view of the protection cover on thehigh-efficiency heat-dissipating fin section 20, (B) of FIG. 11 is afront view of the same, and (C) of FIG. 11 is a side view of the same.

The heat-receiving plate 21, the heat pipe 22, and the fins 23, shown inFIG. 11, are made of aluminum. Particularly, the heat pipe 22 and thefins 23 are small in thickness, which makes them vulnerable to anexternal force, and therefore there is a fear of being deformed thereby.To eliminate this inconvenience, as shown in the figure, the U-shapedprotection cover 30 is rigidly fixed to the heat-receiving plate 21 in amanner covering the high-efficiency heat-dissipating fin section 20. Atthis time, the upper ends of the fins 23 rigidly fixed to the upperportion of the heat pipe 22 and the inside of the protection cover 30are brazed to each other. That is, they are joined to each other suchthat both the thermal conduction and the fixing function are providedthereby. Further, an end (indicated by an arrow A1) of theheat-receiving plate 21 on a side of the bent portion of the heat pipe22 and an end of the inside of the protection cover 30 are brazed toeach other. On the other hand, an end (indicated by an arrow A2) of theheat-receiving plate 21 on a side of an end of the heat pipe 22 and theprotection cover 30 are rigidly fixed to each other with screws, with aheat-resistant resin 31 having a low thermal conductivity interposedtherebetween. The heat-resistant resin 31 is a silicone resin, forexample. The heat-resistant resin is interposed because the temperaturedifferences between the ends of the heat pipe 22 are reduced when theheat of the heat-receiving plate 21 is transferred to an end of theupper portion of the heat pipe 22 via the protection cover 30 and thefins 23, causing lowered heat-transporting efficiency.

As described hereinabove, the high-efficiency heat-dissipating finsection 20 is protected by the protection cover 30 without beingdecreased in heat dissipation efficiency. Further, the protection cover30 and part of the fins 23 brazed to each other attains thereinforcement of the high-efficiency heat-dissipating fin section 20.

Further, a top surface-of the protection cover 30 is formed with a hole32 at a location corresponding to the end of the upper portion of theheat pipe 22. The hole 32 is used for filling liquid in the heat pipe 22from the upper portion of the heat pipe 22 after the protection cover 30has been rigidly fixed to the high-efficiency heat-dissipating finsection 20. The hole 32 is formed such that the liquid can be filled inthe heat pipe 22 after the protection cover 30 has been brazed to thehigh-efficiency heat-dissipating fin section 20 since a temperaturerequired for the brazing normally reaches 400 to 500° C. Therefore, theliquid is evaporated if the brazing is carried out after the liquid hasbeen filled in the heat pipe 22.

It should be noted that the end of the upper portion of the heat pipe 22may be extended downward and a hole may be formed through theheat-receiving plate 21 at a location corresponding to the end of theupper portion of the heat pipe. Due to this construction, the holeformed through the heat-receiving plate 21 is covered when thehigh-efficiency heat-dissipating fin section 20 is mounted on theheat-receiving plate 41 of the heat-dissipating fin section 40. Thismake it possible to prevent an external force deforming the protectioncover 30 starting from a hole formed therethrough.

As shown in (A) of FIG. 11, the heat-receiving plate 21 of thehigh-efficiency heat-dissipating fin section 20 is formed with screwholes 21 a to 21 h, referred to hereinafter, for fixing the poweramplifier unit 86 appearing in FIG. 8 to the heat-receiving plate 21with the heat-receiving plate 41 of the heat-dissipating fin section 40interposed therebetween.

FIG. 12 is a cross-sectional view of the high-efficiencyheat-dissipating fin section taken on line A—A of FIG. 9. As shown inFIG. 12, the heat-receiving plate 41 of the heat-dissipating fin section40 is formed with a hole 45 for fitting the high-efficiencyheat-dissipating fin section 20 therein. The hole 45 has a size largeenough to allow the fins 23 of the high-efficiency heat-dissipating finsection 20 to pass therethrough and a flange 45 a formed on the rimthereof, for having the periphery of the heat-receiving plate 21 fixedthereto. The periphery of the heat-receiving plate 21 is in contact withthe flange 45 a, and rigidly fixed to the same with screws 24 a, 24 b.Although only two screws are shown in FIG. 12, actually, three or morescrews are used for fixing the periphery of the heat-receiving plate 21.

The power amplifier unit 86 is rigidly fixed to the heat-receiving plate21 of the high-efficiency heat-dissipating fin section 20 with thescrews 24 a. The screws 24 a also play the role of a shield by rigidlyfixing the power amplifier unit 86 to the heat-receiving plate 21.Although in FIG. 12, only one screw 24 a is shown as such a screw,actually, a plurality of screws 24 a are used for fixing the poweramplifier unit 86 to the heat receiving plate 21. It should be notedthat the power amplifier unit 86 and the heat-receiving plate 21 areelectrically insulated from each other.

The heat-receiving plate 21 of the high-efficiency heat-dissipating finsection 20 is formed with counterbores 21 i such that the transistors 86a to 86 g (the transistor 86 e is shown in FIG. 12) of the poweramplifier unit 86 shown in FIG. 9 are in direct contact with theheat-receiving plate 21.

As described above, the heat-receiving plate 41 of the heat-dissipatingfin section 40 is formed with the hole 45, the power amplifier unit 86is secured to the high-efficiency heat-dissipating fin section 20, andthe transistors 86 a to 86 g which generate high-temperature heat arebrought into contact with the heat-receiving plate 21. This makes itpossible to attain the efficient dissipation of the high-temperatureheat from the transistors. Further, since the hole 45 is formed throughthe heat-receiving plate 41 of the heat-dissipating fin section 40, theweight of the heat-receiving plate 41 is reduced, which contributes toweight reduction.

Now, when the power amplifier unit 86 is secured to the heat-receivingplate 21, the power amplifier unit 86 is required to be fixed such thatthe transistors 86 a to 86 g and a wiring pattern thereon are positionedto the counterbores 21 i and the terminals of input/output connectorsmounted on the heat-receiving plate 41 of the heat-dissipating finsection 40. This is because the electric characteristics of the poweramplifier unit 86 are adversely affected by the displacement ofpositions of the transistors 86 a to 86 g and the terminals of theinput/output connectors, since the power amplifier unit 86 deals with ahigh-frequency signal.

To eliminate the above inconvenience, the screw hole 21 a shown in FIG.11 has an accurate hole diameter with almost no play between the screwhole 21 a and the screw for fixing the power amplifier unit 86. Thescrew hole 21 d is a hole which has an elliptical shape longer in thedirection of a straight line connecting the screw hole 21 a and thescrew hole 21 d so as to absorb slight displacement of the poweramplifier unit 86. The screw hole 21 d has a minor diameter which isaccurate and has almost no play between the screw hole 21 d and thescrew for fixing the power amplifier unit 86. This makes it possible toaccurately position the power amplifier unit 86 in a directionperpendicular to the direction of the straight line connecting the screwhole 21 a and the screw hole 21 d. The screw holes 21 b, 21 c, and 21 eto 21 h have a diameter slightly larger than that of the screws forfixing the power amplifier unit 86 to provide a margin for displacementof the power amplifier unit 86.

It should be noted that when the size of the screws for fixing the poweramplifier unit 86 is set to M3, the diameter of the screw hole 21 a is3.2 mm, and the diameter of the screw holes 21 b, 21 c, and 2le to 21 his 3.6 mm. The minor diameter of the screw hole 21 d is 3.2 mm, and themajor diameter of the same is 3.6 mm.

FIG. 13 is a diagram showing a variation of the construction shown inFIG. 12. As shown in FIG. 13, in this variation, the heat-receivingplate 41 of the heat-dissipating fin section 40 is formed with holes 46having the respective sizes same as those of the transistors 86 a to 86h (the transistor 86 e is shown in FIG. 13) mounted on the poweramplifier unit 86. The heat-receiving plate 21 of the high-efficiencyheat-dissipating fin section 20 is formed with protrusions 21 j forbeing fitted in the holes 46 formed through the heat-receiving plate 41of the heat-dissipating fin section 40, respectively. The protrusions 21j are configured to be in contact with the transistors 86 a to 86 g,shown in FIG. 9, of the power amplifier unit 86.

As described above, the holes 46 having the same sizes as those of thetransistors 86 a to 86 h of the power amplifier unit 86 are formedthrough the heat-receiving plate 41 of the heat-dissipating fin section40, and the protrusions 21 j are formed on the heat-receiving plate 21of the high-efficiency heat-dissipating fin section 20, for being fittedin the holes 46, respectively, whereby the heat-receiving plate 21 andthe transistors 86 a to 86 h are brought into direct contact with eachother. This also contributes to efficient heat dissipation.

FIG. 14 is a perspective view showing the communication device having acover mounted thereon. FIG. 15 is a cross-sectional view of the FIG. 14communication device, which is useful in explaining a flow of airthrough the communication device. The communication device has astep-shaped cover 90 for covering the fins 23 of the high-efficiencyheat-dissipating fin section 20 and the fins 42 of the heat-dissipatingfin section 40, different in height. The cover 90 plays the role of aduct such that cooling air blown from the cooling fan 71 appearing inFIG. 2 passes between the fins 23 of the high-efficiencyheat-dissipating fin section 20 and the fins 42 of the heat-dissipatingfin section 40.

FIG. 16 is a cross-sectional view of the communication device, on whichanother cover is attached thereto, for comparison of flows of coolingair passing between fins. As shown in FIG. 16, the cover 91 covering thecommunication device 10 of FIG. 16 is not configured to cover the fins42 of the heat-dissipating fin section 40 although it is configured tocover the fins 23 of the high-efficiency heat-dissipating fin section20.

On the other hand, the cover 90 in FIG. 15 is configured to cover thefins 23 of the high-efficiency heat-dissipating fin section 20 and thefins 42 of the heat-dissipating fin section 40, which causes cooling airhaving passed between the fins 23 to pass between the fins 42, asindicated by arrows in FIG. 15. However, the FIG. 16 cover 91 is notconfigured to cover the fins 42 of the heat-dissipating fin section 40,so that almost all cooling air having passed between the fins 23 iscaused to pass outside an area of the fins 42 by resistance offered bythe fins 42, as indicated by arrows in FIG. 16.

Thus, according to the preferred embodiment, the cover 90 covering thefins 23 of the high-efficiency heat-dissipating fin section 20 and thefins 42 of the heat-dissipating fin section 40 causes cooling air blownfrom the cooling fan 71 to pass between the fins 23 and the fins 42,whereby it is possible to attain efficient heat dissipation.

Further, by causing cooling air to pass between the fins 42 of theheat-dissipating fin section 40, it is possible to improve the heatdissipation efficiency of the fins 42, and thereby reduce the size andweight of the heat-dissipating fin section 40.

Further, assuming that the heat dissipation efficiency is enhancedwithout using the high-efficiency heat-dissipating fin section 20, thatis, by using e.g. only one heat-dissipating fin section increased in thesurface area of a heat-receiving plate thereof (the number of fins),there is an increased pressure loss of cooling air blown from thecooling fan 71. This makes it necessary to increase the capacity of thecooling fan 71 appearing in FIG. 2. In the present invention, however,the high-efficiency heat-dissipating fin section 20 is mounted on orprovided for the high-temperature heat-generating section, and theheat-dissipating fin section 40 is mounted on or provided for thelow-temperature heat-generating section, which makes it possible toreduce the size of the fins 42 of the heat-dissipating fin section 40,and thereby reduce the pressure loss of cooling air. Therefore, it isnot necessary to use the cooling fan 71 increased in capacity, whichcontributes to cost reduction.

Furthermore, when heat dissipation is carried out for both of thehigh-temperature heat-generating section and the low-temperatureheat-generating section using only one heat-dissipating fin sectionwithout using the high-efficiency heat-dissipating fin section 20, it isnecessary to design the high-temperature heat-generating section suchthat it is located closer to the cooling fan 71 than the low-temperatureheat-generating section, which causes the degree of freedom in design tobe lost. This is because heat is transferred from a high temperatureside to a low temperature side, and for efficient heat dissipation, itis necessary to allow heat generated by the high-temperatureheat-generating section to be transferred to fins at a locationcorresponding to the low-temperature heat-generating section (if thehigh-temperature heat-generating section is disposed leeward of thelow-temperature heat-generating section, the direction of flow of air isopposite to the direction of transfer of heat, and no fins are providedat a location leeward of the high-temperature heat-generating section,which makes it to impossible to perform efficient dissipation using thecooling fan 71). In the present invention, the high-efficiencyheat-dissipating fin section 20 is mounted on or provided for thehigh-temperature heat-generating section, and the heat-dissipating finsection 40 is mounted on or provided for the low-temperatureheat-generating section, to thereby enhance the heat dissipationefficiency of the communication device. This makes it possible to designthe communication device such that the high-temperature heat-generatingsection is located leeward of the low-temperature heat-generatingsection, and therefore prevent the degree of freedom in design frombeing lost. It should be noted that although in the communication device10 described above, the high-temperature heat-generating section and thelow-temperature heat-generating section are located on the windward sideand the leeward side, respectively, with respect to the flow of coolingair blown by the cooling fan 71, this is not limitative, but theirpositions may be reversed.

As described hereinbefore, according to the present invention, a firstheat-dissipating fin section, which includes fins provided on a heatpipe, for efficient heat dissipation, is mounted on or provided for ahigh-temperature heat-generating section that generates high-temperatureheat, while a second heat-dissipating fin section, which includes finsprovided on a heat-receiving plate, is mounted on or provided for alow-temperature heat-generating section that generates low-temperatureheat.

As a result, it is possible to efficiently dissipate heat locallygenerated, without producing portions of the heat-dissipating finsection to which the heat is not uniformly transferred due to anincrease in the size of the heat-dissipating fin section.

Further, since the high-temperature heat generated by thehigh-temperature heat-generating section is efficiently dissipated bythe first heat-dissipating fin section, the second heat-dissipating finsection is only required to have a shape suitable for dissipation of theheat generated by the low-temperature heat-generating section. Thismakes it possible to reduce the size and weight of the communicationdevice.

The foregoing is considered as illustrative only of the principles ofthe present invention. Further, since numerous modifications and changeswill readily occur to those skilled in the art, it is not desired tolimit the invention to the exact construction and applications shown anddescribed, and accordingly, all suitable modifications and equivalentsmay be regarded as falling within the scope of the invention in theappended claims and their equivalents.

1. A communication device that generates heat, comprising: ahigh-temperature heat-generating section that generates high-temperatureheat; a first heat-dissipating fin section mounted on saidhigh-temperature heat-generating section, said first heat-dissipatingfin section having a heat pipe and fins provided on said heat pipe; alow-temperature heat-generating section that generates low-temperatureheat having a lower temperature than that of the high-temperature heatgenerated by said high-temperature heat-generating section; a secondheat-dissipating fin section mounted on said low-temperatureheat-generating section, said second heat-dissipating fin section havinga heat-receiving plate, and fins provided on said heat-receiving plate;and a protection cover for covering said first heat-dissipating finsection, wherein said fins provided on said heat pipe are fixed to saidprotection cover, said first heat-dissipating fin section has aheat-receiving plate having said heat pipe disposed thereon, and saidprotection cover is fixed to said heat-receiving plate having said heatpipe disposed thereon, via a heat-resistant resin having a low thermalconductivity.
 2. The communication device as claimed in claim 1, whereinan inside of said protection cover and said fins of said firstheat-dissipating tin section are rigidly fixed to each other by brazing.3. The communication device as claimed in claim 1, wherein said firstheat-dissipating fin section has a heat-receiving plate having said heatpipe disposed thereon, wherein said high-temperature heat-generatingsection includes a printed board, and wherein said printed board isrigidly fixed to said heat-receiving plate having said heat pipedisposed thereon.
 4. The communication device as claimed in claim 1,wherein said first heat-dissipating fin section has a beat-receivingplate having said heat pipe disposed thereon, wherein saidhigh-temperature heat-generating section includes components thatgenerate heat, and wherein said components are in contact with saidheat-receiving plate having said heat pipe disposed thereon.
 5. Thecommunication device as claimed in claim 4, wherein said components aretransistors.
 6. A communication device that generates heat, comprising:a high-temperature heat-generating section that generateshigh-temperature heat; a first heat-dissipating fin section mounted onsaid high-temperature heat-generating section, said firsthear-dissipating fin section having a heat pipe and fins provided onsaid heat pipe; a low-temperature hear-generating section that generateslow-temperature heat having a lower temperature than that of thehigh-temperature heat generated by said high-temperature heat-generatingsection; a second heat-dissipating fin section mounted on saidlow-temperature heat-generating section, said second heat-dissipatingfin section having a heat-receiving plate, and fins provided on saidheat-receiving place; and an air duct cover for covering said fins ofsaid first heat-dissipating fin section and said fins of said secondheat-dissipating fin section to cause air from a cooling fan to passbetween said fins of said first heat-dissipating fin section and saidfins of said second heat-dissipating fin section.